U.S. patent number 5,936,421 [Application Number 08/990,299] was granted by the patent office on 1999-08-10 for coaxial double-headed spring contact probe assembly and coaxial surface contact for engagement therewith.
This patent grant is currently assigned to Virginia Panel Corporation. Invention is credited to Paul D. Blackard, Henri T. Burgers, Jeffrey P. Stowers.
United States Patent |
5,936,421 |
Stowers , et al. |
August 10, 1999 |
Coaxial double-headed spring contact probe assembly and coaxial
surface contact for engagement therewith
Abstract
An electrical test probe assembly for loaded board testing
includes a housing having a hollow interior, and first and second
opposite shields positioned and axially slidable in the housing and
outwardly biased against each other. The first and second opposite
shields form first and second shield cavities, respectively. In
addition, the electrical test probe assembly includes first and
second opposite insulators positioned and axially slidable in the
first and second shield cavities, respectively. The first and
second opposite insulators form an insulator cavity extending along
the housing. Finally, the electrical test probe assembly includes
first and second opposite plungers positioned and axially slidable
in the insulator cavity of the first and second opposite insulators
and outwardly biased against each other.
Inventors: |
Stowers; Jeffrey P. (Mt.
Sydney, VA), Burgers; Henri T. (Grottoes, VA), Blackard;
Paul D. (Waynesboro, VA) |
Assignee: |
Virginia Panel Corporation
(Waynesboro, VA)
|
Family
ID: |
26982529 |
Appl.
No.: |
08/990,299 |
Filed: |
December 15, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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688973 |
Jul 31, 1996 |
5850147 |
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320514 |
Oct 11, 1994 |
5576631 |
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Current U.S.
Class: |
324/750.27;
324/755.02 |
Current CPC
Class: |
G01R
15/12 (20130101) |
Current International
Class: |
G01R
15/12 (20060101); G01R 15/00 (20060101); G01R
015/12 () |
Field of
Search: |
;324/754,755,761,762,72.5 ;439/482,824,700 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0127466 |
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Jul 1985 |
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JP |
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0098566 |
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Apr 1988 |
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JP |
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Other References
"Spring Plunger Contact", by Buyck et al., IBM Tech Disc. Bull.,
vol. 15, No. 1, Jun. 1972, p. 58..
|
Primary Examiner: Nguyen; Vinh P.
Attorney, Agent or Firm: Donner; Irah H. Pepper Hamilton
LLP
Parent Case Text
RELATED APPLICATIONS
This application is a continuing U.S. application of application
Ser. No. 08/688,973 filed Jul. 31, 1996, (now U.S. Pat. No.
5,850,147) which is a continuation-in-part of patent application
Ser. No. 08/320,514, filed Oct. 11, 1994, now U.S. Pat. No.
5,576,631.
Claims
What is claimed is:
1. An electrical test probe assembly for loaded board testing,
comprising:
a housing having a hollow interior;
first and second opposite shields positioned and axially slidable
in said housing and outwardly biased against each other, said first
and second opposite shields forming first and second shield
cavities, respectively;
first and second opposite insulators positioned and axially
slidable in said first and second shield cavities, respectively,
said first and second opposite insulators forming an insulator
cavity extending along the housing; and
first and second opposite plungers positioned and axially slidable
in said insulator cavity of said first and second opposite
insulators and outwardly biased against each other.
2. The electrical test probe assembly according to claim 1, wherein
axial movement of said first insulator will cause axial movement of
said first plunger.
3. The electrical test probe assembly according to claim 1, wherein
axial movement of said first shield drives axial movement of said
first insulator, and axial movement of said first insulator drives
axial movement of said first plunger.
4. The electrical test probe assembly according to claim 1, wherein
axial movement of said first insulator drives axial and rotational
movement of said first plunger.
5. The electrical test probe assembly according to claim 1, wherein
said first and second opposite insulators are inwardly biased by
and secured within the housing by said first and second opposite
shields, respectively.
6. The electrical test probe assembly according to claim 1, wherein
said first and second opposite plungers respectively limit inner
movement of said first and second opposite insulators in said
housing, and said first and second opposite plungers outwardly bias
said first and second opposite insulators.
7. The electrical test probe assembly according to claim 1, wherein
said first and second opposite plungers and said first and second
opposite shields are independently biased.
8. The electrical test probe assembly according to claim 1, wherein
said first and second opposite plungers are biased by a first
spring, and said first and second opposite shields are biased by a
second spring.
9. The electrical test probe assembly according to claim 1, wherein
one of said first and second insulators is inserted and axially
slidable in another of said first and second insulators.
10. The electrical test probe assembly according to claim 1,
wherein said first and second opposite plungers include outer
portions extending through respective opposite open ends of the
housing, each of said first and second opposite plungers
terminating in a contact tip outside the housing, said first
opposite plunger having a receptacle extending into the housing
with a keyway in the receptacle, said second opposite plunger
having a twisted guide member extending through the housing into
the keyway of said first opposite plunger, and axial translation of
said first and second plungers relative to each other causes each
of said first and second opposite plungers to rotate.
11. The electrical test probe assembly of claim 10, wherein the
contact tip of said first opposite plunger comprises inwardly
directed leaves for engaging a contact probe head inserted
therein.
12. The electrical test probe assembly according to claim 1,
wherein said housing includes first and second opposite ends each
having restricted apertures for limiting axial travel of said first
and second opposite shields.
13. The electrical test probe assembly according to claim 1,
wherein said first opposite plunger includes a receptacle extending
into the housing with a keyway in the receptacle, and said second
opposite plunger includes a twisted guide member extending through
the housing into the keyway of said first opposite plunger, and
wherein the twisted guide member of said second opposite plunger
includes a bearing surface formed by a wall of a channel formed
therein, and a spiral channel formed along a length of the twisted
guide member.
14. The electrical test probe assembly according to claim 13,
wherein said second opposite plunger further includes a cylindrical
member having a first helical channel forming a bearing surface for
engaging the keyway of said first opposite plunger.
15. The electrical test probe assembly according to claim 14,
wherein said second opposite plunger further comprises a second
helical channel formed opposite said first helical channel in said
cylindrical member.
16. The electrical test probe assembly according to claim 15,
wherein the keyway includes radially extending tabs engaging said
first and second helical channels.
17. The electrical test probe assembly according to claim 13,
wherein the keyway is geometrically shaped as a regular
polygon.
18. The electrical test probe assembly according to claim 1,
wherein said housing includes a collar portion for longitudinal
retention of said housing in a mounting member.
19. The electrical test probe assembly according to claim 1,
wherein said housing has necked down portions at opposite ends
thereof to limit travel of said first and second opposite
plungers.
20. The electrical test probe assembly according to claim 1,
wherein said first opposite plunger further comprises an elongated
leafspring formed adjacent to the keyway for engaging said second
opposite plunger against lateral movement during rotational
movement of said second opposite plunger.
21. An electrical test probe assembly for loaded board testing,
comprising:
a housing having a hollow interior;
first and second opposite shields positioned and axially slidable
in said housing and outwardly biased, said first and second
opposite shields forming first and second shield cavities,
respectively;
first and second opposite insulators positioned and axially
slidable in said first and second shield cavities, respectively,
said first and second opposite insulators forming an insulator
cavity extending along the housing; and
first and second opposite plungers positioned and axially slidable
in said insulator cavity of said first and second opposite
insulators and outwardly biased.
22. The electrical test probe assembly according to claim 21,
wherein said first and second opposite insulators are biased
inwardly by said first and second opposite shields,
respectively.
23. The electrical test probe assembly according to claim 21,
wherein said first and second opposite insulators are biased
outwardly by said first and second opposite plungers,
respectively.
24. The electrical test probe assembly according to claim 21,
wherein said first and second opposite shields are biased outwardly
by said first and second opposite insulators, respectively.
25. The electrical test probe assembly according to claim 21,
wherein said first and second opposite plungers are biased inwardly
by said first and second opposite insulators, respectively.
26. An electrical test probe assembly for loaded board testing,
comprising:
a housing having a hollow interior;
first and second opposite shields positioned and axially slidable
in said housing and outwardly biased against each other, said first
and second opposite shields forming a shield cavity;
first and second opposite insulators positioned in said shield
cavity, said first and second opposite insulators forming an
insulator cavity extending along the housing; and
first and second opposite plungers positioned and axially slidable
in said insulator cavity of said first and second opposite
insulators and outwardly biased.
27. An electrical test probe assembly for loaded board testing
according to claim 26, wherein said first and second opposite
insulators, said first and second opposite plungers and said first
and second opposite shields are disposed in said housing and said
housing comprises as a single integral piece.
28. An electrical test probe assembly for loaded board testing,
comprising:
a housing having a hollow interior;
first and second opposite shields positioned and axially slidable
in said housing and outwardly biased, said first and second
opposite shields forming a shield cavity;
first and second opposite insulators positioned in said shield
cavity, said first and second opposite insulators forming an
insulator cavity extending along the housing; and
first and second opposite plungers positioned and axially slidable
in said insulator cavity of said first and second opposite
insulators and outwardly biased against each other.
29. An electrical test probe assembly for loaded board testing
according to claim 28, wherein said first and second opposite
insulators, said first and second opposite plungers and said first
and second opposite shields are disposed in said housing as a
single integral piece and said housing comprises as a single
integral piece.
30. An electrical test probe assembly for loaded board testing,
comprising:
a housing having a hollow interior;
first and second opposite shields positioned and axially slidable
in said housing and outwardly biased, said first and second
opposite shields forming a shield cavity, said first and second
opposite shields having respective first and second shield ends,
and at least one of the first and second shield ends being tapered
for engagement with an external surface having a corresponding
taper;
first and second opposite insulators positioned in said shield
cavity, said first and second opposite insulators forming an
insulator cavity extending along the housing; and
first and second opposite plungers positioned and axially slidable
in said insulator cavity of said first and second opposite
insulators and outwardly biased.
31. A method of providing electrical connection using a contact
probe for loaded board testing, comprising the steps of:
(a) providing a housing for the double-headed spring contact
probe;
(b) providing first and second shields forming a shield cavity to
axially slide in the housing;
(c) outwardly biasing the first and second shields;
(d) providing first and second insulators to axially slide in the
shield cavity of the first and second shields, the first and second
insulators forming an insulator cavity extending through the
housing;
(e) providing first and second plungers to axially slide relative
to each other in the insulator cavity formed by the first and
second insulators, and to transmit a signal through the contact
probe; and
(f) outwardly biasing the first and second plungers.
32. An electrical test probe assembly for loaded board testing,
comprising:
a housing having a hollow interior;
first and second opposite shields positioned and axially slidable
in said housing and outwardly biased, said first and second
opposite shields forming first and second shield cavities,
respectively;
first and second opposite insulators positioned and axially
slidable in said first and second shield cavities, respectively,
said first and second opposite insulators forming an insulator
cavity extending along the housing; and
first and second opposite plungers positioned and axially slidable
in said insulator cavity of said first and second opposite
insulators and outwardly biased.
33. An electrical test probe assembly for loaded board testing,
comprising:
a housing having a hollow interior;
first and second opposite shields positioned in said housing and
outwardly biased, said first and second opposite shields forming
first and second shield cavities, respectively;
first and second opposite insulators positioned and axially
slidable in said first and second shield cavities, respectively,
said first and second opposite insulators forming an insulator
cavity extending along the housing; and
first and second opposite plungers positioned and axially slidable
in said insulator cavity of said first and second opposite
insulators and outwardly biased.
34. An electrical test probe assembly for loaded board testing
according to claim 33, wherein said first and second opposite
insulators are outwardly biased by said first and second opposite
plungers and inwardly biased by said first and second opposite
shields.
Description
TECHNICAL FIELD
The invention relates to electrical probes and, more particularly,
to miniature spring-loaded probes for providing electrical contact
between electrical components having coaxial-type connections.
BACKGROUND ART
Testing, diagnosis, maintenance and calibration of electronic
devices often require supplying test signals to, and receiving
signals from, components of a Device Under Test (DUT) or Unit Under
Test (UUT). When an electronic device is fabricated on one or more
circuit boards, electronic components mounted on the circuit boards
may not be accessible for testing using existing circuit board
mounted connectors. Therefore, connections to components to be
tested are made using external electrical probes applied to the
exposed leads of the components and/or to a printed circuit board
wiring layer.
Automatic testing of electrical circuits requires simultaneous
connection to many circuit test points. The automatic testing
equipment simultaneously supplies signals to, and receives signals
from, combinations of test points. A conventional test fixture used
to electrically probe a circuit card of a DUT includes a "bed of
nails" having a platform for supporting the circuit card and an
array of single headed spring probes. Each spring probe includes a
probe head which makes positive electrical contact with an
overlying portion of the circuit board being tested. An opposite
end of each probe is connected to test equipment through single
point wiring.
A conventional single headed electrical test probe is described by
Johnston et al., U.S. Pat. No. 5,032,787 issued Jul. 16, 1991,
incorporated herein by reference. The Johnston et al. patent
describes a test probe assembly including a barrel having a hollow
interior and a plunger which slides axially in the barrel. The
plunger has an outer portion extending through an open end of the
barrel, terminating in a contact tip outside the barrel for contact
with a test point and a hollow, elongated receptacle extending
through the barrel. The receptacle has a square or rectangular
pilot hole so that an elongated fixed guide member in the barrel
extends through the pilot hole. The guide member extends through
the interior of the barrel away from the pilot hole and has an
cuter surface which engages the pilot hole. A spring inside the
barrel extends along the guide member and is biased against the
internal end of the receptacle inside the barrel.
Axial travel of the Johnston et al. plunger into the barrel is
against the spring bias. The outer surface of the guide member
engages the correspondingly shaped pilot hole and controls
rotational motion of the plunger as it travels along the guide
member against the bias of the spring. The guide member is not free
to rotate or axially translate through the barrel, i.e., rotate
while being depressed in toward the barrel. End 58 of conductive
guide member 54 projects out from the end of the barrel to provide
an anti-rotational detail for the probe assembly. Cylindrical
terminal portion 60 of the end cylindrical section 56 is described
as being rigidly affixed to the inside of the barrel. Terminal
portion 62 of the guide member projects outside the barrel to
provide anti-rotation. Thus, the Johnston et al. probe is useful to
connect a dedicated test lead to a single component or conductive
layer on one circuit board via rotation of the guide member.
Another example of a conventional spring probe assembly is
illustrated in Langgard, U.S. Pat. No. 5,175,493 issued on Dec. 29,
1992. The spring probe assembly includes an outer barrel having an
open end and a remote end, an inner core of dielectric material,
and an electrical contact spring probe. A shield surrounds the
inner core between the barrel and the core and extends the full
length of the barrel. The inner core is fixed within the outer
barrel, and the shield is biased against the outer barrel. In one
embodiment, a double ended probe assembly includes two electrical
contact probes. The double ended probe assembly is the same as the
single probe assembly, but the axial bore includes two spring
probes in back-to-back relationship. An elongated barrel is used
which has center connector pins joining the structure together.
Thus, Langgard merely utilizes the same structure, and provides no
unique structure for creating a double ended probe assembly. In
addition, Langgard provides no method or structure whatsoever for
effectively and efficiently connecting the shielded contact
assembly with a coaxial conductor. Rather, Langgard requires end to
end abutment or overlap and soldering techniques to provide a good
electrical connection between the probe assembly and a coaxial
conductor. Thus, in Langgard, the probe assembly is generally
affixed to the coaxial conductor when the coaxial conductor is in
use.
Since testing equipment and other electronic equipment must
typically be adapted to varied uses, it is often necessary to
reconfigure signal connections and condition signals to interface
the equipment to a particular DUT. This can be accomplished by
dedicated wiring, patch panels, and/or using appropriate signal
routing/conditioning interface equipment in the form of a
personality board. A personality board is connected between a
testing device and a DUT to properly route and condition signals
between the two devices. Thus, a testing device is electrically
adapted to a particular DUT by using an appropriate personality
board. Substitution of personality boards allows a single testing
device to be used with a plurality of DUTs.
The testing device is connected to a personality board which, in
turn, is connected to a test fixture holding the DUT using
conventional electrical connectors and cabling. Thus, the
personality board is used to electrically correct two devices.
However, the additional wiring used to connect the personality
board can impair signal connectivity and degrade the transmitted
signals. The added connectors and cables also increase device cost
and require additional mounting space on each circuit board and
between circuit boards. Further, the device connectors are subject
to misalignment and introduce maintenance and reliability problems.
Multiple connectors and cabling also complicate the substitution of
personality boards. Further, we have discovered that most prior art
probes, such as Johnson et al., only provide one-sided connection
where, as in Johnson et al. only the guide member rotates.
We have discovered, however, that a need exists for a connector
system providing easy installation and replacement of circuit board
mounted devices.
We have further discovered that a need exists for a low resistance
electrical connector for interfacing circuits and wiring mounted on
opposing circuit boards.
In addition, we have discovered that a need exists for a
reconfigurable connector system for interfacing various nodes of an
electronic device to a corresponding point of a second electronic
device without intervening connectors.
We have further discovered that for more critical testing
conditions where the transmitted signals are more susceptible to
noise or environmental conditions, there is a need to transmit
testing signals with higher accuracy.
We have also discovered that for more complicated testing
conditions where many signals are required to be transmitted
between the DUT and the testing device via the personality board,
there is a need to more effectively and efficiently utilize the
limited space to transmit these greater number of testing
signals.
We have also discovered that it is desirable to effectively and
efficiently connect a coaxial shielded contact assembly with a
coaxial conductor.
We have also discovered that it is desirable to eliminate the need
for end to end abutment or overlap and soldering techniques to
provide a good electrical connection between the probe assembly and
a coaxial conductor.
We have also discovered that it is desirable to eliminate the need
for the probe assembly to be affixed to the coaxial conductor.
We have further discovered that it is desirable that the structure
of the coaxial spring probe assembly permit all components to be
movably connected to one another.
DISCLOSURE OF THE INVENTION
A feature and advantage of the invention is to provide a connector
and connector system permitting ready installation and replacement
of circuit boards requiring frequent changing.
Another feature and advantage of the invention is to provide a
connector and connector system for directly connecting electronic
circuitry on opposing parallel circuit cards.
Another feature and advantage of the invention is to provide a low
loss signal path between electronic devices.
A further feature and advantage of the invention is to provide a
universal array of connectors for electrically interfacing a
variety of electronic devices.
Another feature and advantage of the invention is to transmit
testing signals with higher accuracy for more critical testing
conditions where the transmitted signals are more susceptible to
noise or environmental conditions.
Another feature and advantage of the invention is to more
effectively and efficiently utilize the limited space to transmit a
greater number of testing signals for more complicated testing
conditions where many signals are required to be transmitted
between the DUT and the testing device via the personality
board.
Another feature and advantage of the invention is to effectively
and efficiently connect a coaxial shielded contact assembly with a
coaxial conductor.
Another feature and advantage of the invention is to eliminate the
need for end to end abutment or overlap and soldering techniques to
provide a good electrical connection between the probe assembly and
a coaxial conductor.
Another feature and advantage of the invention is to eliminate the
need for the probe assembly to be affixed to the coaxial
conductor.
Another feature and advantage of the invention is to provide a
coaxial spring probe assembly that permits many or all components
therein to be movably connected to one another.
According to one aspect of the invention, a doubleheaded spring
contact probe for loaded board testing includes a barrel having a
hollow interior and opposite plungers which slide axially and are
free to rotate, in the barrel. The plungers have outer portions
which extend through opposite open ends of the barrel, each
terminating in a contact tip outside the barrel for contacting a
test point on a circuit board. One of the plungers has a hollow
receptacle extending into the barrel with a rectangular or notched
keyway opening into the receptacle. The other plunger has a twisted
guide member extending through the barrel into the keyway of the
other plunger whereby axial translation of the plungers relative to
each other causes relative rotation thereof. A spring engages
opposite shoulder or collar portions of the plungers to bias the
plungers outwardly against opposite ends of the barrel. Necked
portions of the barrel limit travel of the plungers out from the
barrel.
Rotation of the probe ends improve the resultant contact of the
probe with the circuit board under test or a companion personality
board as the rotating ends sweep oxide off of the contact area. The
invention also exhibits improved electrical conductivity between
plungers by providing a straight line current path between
plungers, conductivity between the plungers provided by engagement
of the guide member at the keyway opening. The double-headed
construction further accommodates direct Printed Circuit (PC) board
to PC board electrical connection.
According to another aspect of the invention, an electrical probe
includes a housing having first and second opposite open ends. A
first elongated plunger is partially positioned within the housing.
A first portion of the first plunger extends out from the housing
through the first opening end and terminates in a first electrical
contact probe. A second portion of the first elongated plunger is
rod-like, and is lengthwise contiguous with the first portion. The
second portion is positioned within the housing and includes a
bearing surface for transmitting a torque.
A second elongated plunger is likewise partially positioned within
the housing. A first portion extends out from the housing through
the second open end of the housing and terminates in a second
electrical contact probe head. The second portion of the second
elongated plunger is tubular, lengthwise contiguous with the first
portion, and is positioned within the housing. The second rod-like
portion of the first elongated plunger is centrally positioned
within the hollow second portion of the second elongate plunger. An
aperture within the second portion of the second elongated plunger
engages the bearing surface of the first elongated plunger.
A compression spring is positioned within the housing and is
positioned to engage the first and second plungers, biasing the
plungers outward from the housing. The ends of the housing have
restricted apertures for limiting axial travel of the first and
second elongate plungers out from the housing.
According to a feature of the invention, one or more spiral
channels are formed along a length of the second portion of the
first elongate plunger, the bearing surface being formed by one or
more walls of one or more channels. The aperture in the second
elongate member may comprise a keyway and the second portion of the
first elongate plunger may comprise a cylindrical member having a
helical channel forming the bearing surface for engaging the
keyway. The helical channel may subtend a radial angle of between
90 and 150 degrees over the length of the second portion of the
first elongate plunger, an angle of 120 degrees plus or minus five
degrees being preferred.
In a further improvement or additional embodiment of this
invention, the plunger barrel portion is designed for increased
electrical contact with the plunger and its spiral groove.
Specifically, in this embodiment, the keyway for engaging the
plunger channel is disposed at about a 6.degree. angle to the axis
thereof so that the keyway will ride in the plunger channel. In
addition, a leafspring is disposed along the keyway on the barrel
to contact the plunger as it translates along the length of the
barrel. Finally, the plunger barrel portion which normally receives
a solid probe may have mutually spaced leaves inwardly crimped from
the end thereof to engage the probe and retain the same in the
barrel plunger.
In another embodiment of the invention an electrical test probe
assembly for loaded board testing includes a housing having a
hollow interior, and first and second opposite shields positioned
and axially slidable in the housing and outwardly biased against
each other. The first and second opposite shields form first and
second shield cavities, respectively. In addition, the electrical
test probe assembly includes first and second opposite insulators
positioned and axially slidable in the first and second shield
cavities, respectively. The first and second opposite insulators
form an insulator cavity extending along the housing. Finally, the
electrical test probe assembly includes first and second opposite
plungers positioned and axially slidable in the insulator cavity of
the first and second opposite insulators and outwardly biased
against each other.
In addition, a method of providing electrical connection using a
double-headed spring contact probe for loaded board testing is
provides. The method includes the steps of providing a barrel for
the double-headed spring contact probe, and providing first and
second shields having first and second shield cavities to axially
slide in the barrel and to transmit a first signal through the
double-headed spring contact probe via the first and second
shields. The method further includes the steps of outwardly biasing
the first and second shields, and providing first and second
insulators to axially slide in the first and second shield cavities
of the first and second shields respectively. The method also
includes the steps of providing first and second plungers to
axially slide relative to each other in the insulator cavity formed
by the first and second insulators, and to transmit a second signal
through the double-headed spring contact probe which is
electrically insulated from the first signal, and outwardly biasing
the first and second plungers.
An electrical test probe assembly for loaded board testing includes
a housing having a hollow interior and first and second opposite
shields. The first and second opposite shields are positioned and
axially slidable in the housing. The first and second opposite
shields form a shield cavity and have respective first and second
shield ends. At least one of the first and second shield ends is
tapered for engagement with an external surface having a
corresponding taper. The electrical test probe assembly also
includes first and second opposite insulators positioned in the
shield cavity. The first and second opposite insulators form an
insulator cavity extending along the housing. The electrical test
probe assembly also includes first and second opposite plungers
positioned and axially slidable in the insulator cavity of the
first and second opposite insulators and are outwardly biased.
A coaxial surface contact connecting with a coaxial cable includes
a cable center conductor, cable insulator and cable shield. A first
shield forms a first shield cavity, and a second shield connects to
the first shield cavity and forms a second shield cavity. The
coaxial surface contact also includes an insulator positioned in at
least a portion of the first and second shield cavities, and the
insulator forms an insulator cavity. A plunger is positioned in the
insulator cavity of the insulator. The coaxial surface contact also
includes the first coupling connected to the plunger. The first
coupling receives the cable center conductor to electrically
connect the cable center conductor to the plunger, and a second
coupling connects to the second shield. The second coupling
receives the cable shield to electrically connect the cable shield
to the second shield.
The foregoing and other objects, features, aspects and advantages
of the present invention will become more apparent from the
following detailed description of the present invention when taken
in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a partial cross sectional view of a double-headed twist
probe according to the invention;
FIG. 2 is a sectional view of a probe housing prior to insertion of
plungers and crimping of the open insertion end;
FIG. 3 is a partial sectional view of a plunger barrel portion;
FIG. 4 is a partial sectional view of a barrel keyway;.
FIG. 5 is a partial cross-sectional view of a plunger barrel;
FIG. 6 is a side view of a plunger prior to twisting;
FIG. 7 is a side view of a plunger after twisting to form a spiral
channel;
FIG. 8 is a part-al sectional view of a terminal end of a plunger
forming an electrical contact probe head;
FIG. 9 is a cross-sectional view of a plunger showing channel
detail;
FIG. 10 is a partial sectional view of an alternate embodiment of a
double-headed twist probe;
FIG. 11 is a partial sectional side view of a Twin Access Connector
(TAC.TM.) module including an array of double-headed twist probes
providing electrical connectivity between components of a test
device;
FIG. 12 is a partial sectional view of double-headed twist probe
mounted in a module;
FIG. 13 is a partial sectional view of wireless fixture for
interfacing a personality board to a printed circuit board under
test;
FIG. 14 is a partial sectional view of the wireless fixture shown
in FIG. 13 with the printed circuit board positioned to engage the
twist probes;
FIG. 15 is a partial sectional view similar to FIG. 3 illustrating
an alternative embodiment of the plunger barrel portion;
FIG. 16 is a view taken along lines 16--16 of FIG. 15;
FIG. 17 is a view taken along lines 17--17 of FIG. 15;
FIG. 18 is a view taken along lines 18--18 of FIG. 15;
FIG. 19 is a view of a coaxial double-headed twist probe according
to another embodiment of the invention;
FIG. 20 is a partial cross sectional view of a coaxial
double-headed twist probe according to another embodiment of the
invention;
FIG. 21 is a sectional view of a probe housing prior to insertion
of plungers and crimping of the coaxial double-headed twist probe
of FIG. 20;
FIG. 22 is a sectional view of a rear insulator of the coaxial
double-headed twist probe of FIG. 20;
FIG. 23 is a sectional view of a front insulator of the coaxial
double-headed twist probe of FIG. 20;
FIG. 24 is a sectional view of a front shield of the coaxial
double-headed twist probe of FIG. 20;
FIG. 25 is a sectional view of a rear shield of the coaxial
double-headed twist probe of FIG. 20;
FIG. 26 is a side view of a plunger after twisting to form a spiral
channel;
FIG. 27 is a cross-sectional view of a plunger taken along section
lines 27--27 of FIG. 26;
FIG. 28 is a view of a coaxial double-headed twist probe according
to another embodiment of the invention;
FIG. 29 is a partial cross sectional view of a coaxial
double-headed twist probe according to another embodiment of the
invention;
FIG. 30 is a view of a coaxial surface contact or mate according to
another embodiment of the invention;
FIG. 31 is a partial cross sectional view of a coaxial surface
contact according to another embodiment of the invention; and
FIGS. 32-33 are partial cross sectional views illustrating the
engagement between a coaxial surface contact and a coaxial
double-headed twist probe according to another embodiment of the
invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring to FIG. 1, a miniature double-headed twist probe 20
includes a hollow tubular housing 22 having open ends 23 and 24. A
tubular plunger 30 is slidably positioned within central cavity 25
of housing 22, extending outward through aperture 23 and
terminating in contact tip 38. An internal barrel portion 34 of
plunger 30 is coaxial with housing 22, extending approximately to
the midpoint of the housing. Opposing rod-like plunger 50 is
slidably positioned within an opposite portion of cavity 25,
extending out from housing 22 through aperture 24 and terminating
in contact tip 60. An internal twisted rod portion 54 of plunger 50
is shaped like a drill bit or slotted helix, extending through a
matching aperture or keyway 44 of barrel portion 34. Both plungers
30 and 50 are free to rotate and longitudinally translate within
housing 22. External portions of plungers 30 and 50 are made of a
conductive substance such as heat treated beryllium copper (BeCu)
or hardened steel plated with gold over nickel. Housing 22 is
preferably made of a material such as deep drawn gold plated brass
or nickel silver.
Plunger 30 includes lengthwise contiguous internal hollow tubular
or barrel portion 34 and external probe portion 36 which axially
extends out through an aperture in an end of housing 22. A shoulder
portion 42 limits travel of plunger 30, maintaining the probe
within housing 22 by engaging a restricted portion of the aperture
formed by crimping or rolling. An inner face of shoulder portion 42
serves as a seat for spring 70 which biases plunger 30 outward from
housing 22.
Plunger 50 axially extends through an opposite aperture in housing
22 and includes an internal twist rod portion 54 within the housing
and an external probe portion 58 having a terminal contact tip 60.
Internal twist rod 54 is helically formed and includes a twisted
bearing surface 56. Internal twist rod 54 passes through an
aperture forming a keyway 44 in an internal terminal end of barrel
34. Keyway 44 engages twist rod 54, including bearing surfaces 56
thereof so that axial travel of the plungers results in relative
rotation thereof.
Spring 70 is positioned within cavity 25 of housing 22, coaxially
surrounding barrel 34 and twisted rod 54 of the plungers. Spring 70
is made of a spring material such as stainless steel, music wire or
beryllium copper and is positioned within housing 22. Opposite ends
of spring 70 are seated on and engage shoulder portion 42 and
collar portion 62 of plungers 30 and 50, respectively, thereby
biasing the plungers outward from the housing. Inward travel of
plungers 30 and 50 is against an outward bias provided by spring
70.
Housing 22 prior to assembly of the twist probe is shown in FIG. 2
of the drawings. The housing has a substantially tubular body with
an aperture 24 formed at one end while an opposite end 26 remains
open for insertion of the remaining probe components. A bulge in
the housing forms press ring 28 for retaining the twist probe
housing in a support member. After plunger 30, spring 70 and probe
50 are inserted into housing 22, open end 26 is rolled to form a
lip, securing the components within the housing.
Plunger 30 is shown in greater detail in FIGS. 3-5 of the drawings.
Therein, plunger 30 is made of a tubular material such as 360 brass
plated with gold over nickel. Plunger 30 has an open internal
barrel portion 34 and a closed external probe portion 36
terminating in contact tip 38. Shoulder portion 42 bath limits
axial travel of the probe within housing 22, and provides a seating
surface for engaging spring 70, biasing plunger 30 outward from
housing 22. Keyway 44 includes crimped portions 46 forming tabs
extending radially into the cavity 34 of internal barrel 32. These
tabs are configured to engage bearing surface 56 of probe 50.
Referring to FIGS. 6-9, plunger 50 includes an internal rod portion
forming internal twist rod 54. Initially, as shown in FIG. 6, a
straight channel 64a is formed in opposite sides of the surface of
twist rod 54. The rod is then twisted 120 degrees as shown in FIG.
7 so that a spiral groove is formed by the twisted channel 64b.
Channel 64b is configured to engage keyway 44 of plunger 30 whereby
relative axial movement of the probes causes relative rotation of
the probes. Collar portion 62 of plunger 50 limits axial travel of
the probe and forms a seat for the opposite end of spring 70,
biasing probe 50 outward of housing 22 against plunger 30. Shoulder
portion 63 abuts collar portion 62 on the inner portion of plunger
50 and engages an inner surface of spring 70 to maintain coaxial
alignment of the spring within housing 22.
Although the keyway and matching bearing surface of plungers 30 and
50 are shown as inward protruding tabs or "divots" engaging a
channel, other geometric shapes can be used. For example, keyway 44
may comprise a rectangular aperture to engage a plunger having a
corresponding mating rectangular cross-section. The tab/channel
combination, however, has the advantage of increasing
plunger-to-plunger contact surface area thereby minimizing
electrical resistance through the probe.
A further embodiment of the plunger barrel shown in FIGS. 3-5 is
provided in FIGS. 15-18. In that embodiment, the plunger barrel 30'
mounts the inwardly protruding tab or "divot" 44'. However, it is
disposed at an acute angle of about a 6.degree. angle to the
longitudinal axis of the plunger barrel 30' (or an obtuse angle if
viewed in the opposite direction of 174.degree.) to more precisely
accommodate the spiral groove formed by the twisted channel 64b in
twist rod 54. As will be obvious to those skilled in the art, by
providing the keyway 44' at the angle shown, it will engage the
channel 64b for better electrical connection. As shown in FIG. 16,
the keyway 44' is provided on opposite sides of the barrel portion
34 to engage both the grooves 64b in the twist rod 54. In this way,
the keyway 44' will engage the channels and continue to engage the
channels during relative rotational movement of the plungers caused
by relative movement thereof along the common longitudinal
axis.
In addition, with attention to FIGS. 15 and 18, the barrel portion
34 also provides a leafspring 47 having a bearing surface 47' for
contacting the plunger twist rod 54 as it moves axially through the
barrel 30'. As shown in FIG. 18, the leafspring 47 is stamped from
the barrel portion and is integral therewith.
In another embodiment of the invention, spring 22 can be positioned
within internal barrel 34 to bias plungers 30 and 50 axially
outward from housing 22. An alternate construction of the
double-headed twist probe is illustrated in FIG. 10. Housing 22 and
plunger 50 are substantially the same as in the first embodiment of
FIG. 1. However, plunger 30a is constructed of discrete portions
including a barrel portion 34a having a distal end including collar
portion 42a retaining a solid probe 36a. Although this embodiment
requires more machining than is required by the first embodiment,
the discrete solid probe 36a accommodates a greater variety of
geometries for contact tip 38a.
As an alternative to collar portion 42a, as shown in FIGS. 15 and
17, leaves 43 may be provided around the circumference of the open
distal end to facilitate retaining a solid probe. The leaves 43 are
intended to engage a corresponding collar portion (not shown) of a
probe 36 inserted therein.
Another embodiment of the invention is shown in FIG. 11 wherein a
plurality of twist probes are configured in an array to form a Twin
Access Connector (TAC.TM.) module for interfacing test-components
with a personality board. A testing device 100 includes a plurality
of test cards 102 housed in a card cage. Each test card 102 has
attached, to a front plate thereof, an interconnect adaptor 104.
The details of the interconnect adaptor can be found in allowed
U.S. patent application, Ser. No. 07/585,800, filed Sep. 21, 1990,
incorporated herein by reference. A rear TAC module 110 is attached
to the front of interconnect adaptor 104, the combination being
located by receiver frame 106. TAC module 110 includes a plurality
of twist probes 118 providing electrical contact between terminal
ends 109 of cables 108 and a personality board 114. An opposite
face of personality board 114 engages twist probe connectors 112 of
front TAC module 116 to provide electrical conductivity to
connector 122. Device Under Test (DUT) 124 includes corresponding
connectors to engage connector 122 and is supported by support
plate 126.
The TAC modules shown in FIG. 11 permit rapid removal and
replacement of personality board 114 to adapt testing equipment 110
to various DUTs 124. In particular, to change a personality board,
receiver 130 is disengaged, thereby releasing the ITA 120 which
contains front TAC module 116 and personality board 114. Upon minor
disassembly of ITA 120 the personality board 114 can then be
removed and replaced by a new personality board and ITA 120 can be
reassembled. Upon engaging receiver 130, TAC module 116 is brought
back into engagement with personality board 114. Because twist
probes 118 rotate upon depression, oxide on connector pads and
components of personality board 114 is removed, thereby creating a
low resistance connection.
Mounting of a double-headed twist probe 20 in a TAC module 110 is
shown in greater detail in FIG. 12. Housing 22 is inserted into an
aperture 112 in frame 130 of module 110 until press ring 28 engages
a front surface of the frame. Probe 20 is deformably retained in
the aperture as shown. The frame may comprise an insulating
substrate such as plastic with an array of through holes for
receiving probes 20. Peripheral portions of frame 130 include
mounting structures for securing the frame to the front of a card
cage.
Another embodiment of the invention illustrated in FIGS. 13 and 14
incorporates a plurality of double-headed probes to directly
interface a personality board to a circuit board under test. The
probes may be double-headed helix twist probes. Referring to FIG.
13, an interface fixture 200 includes parallel top plate 202 and
alignment plate 204. Plates 202 and 204 are made of a suitable
electrical insulating material such as plastic with a plurality of
aligned through holes. Probes 118 are positioned between the boards
with opposite ends of the probes extending through respective
vertically aligned through holes of plates 202 and 204. The through
holes have diameters greater than a housing diameter of probes 118
positioned therein but less than the diameter of retaining rings
28a and 28b formed proximate opposite ends of the housings. Upward
axial translation of probes 118 through the through holes is
constrained by engagement of upper retaining ring 28a by
surrounding portions of top plate 202 and downward translation is
limited by lower retaining ring 28b engaging surrounding portions
of alignment plate 204.
Fixture 200 is positioned above a personality board 114 so that
lower external probe portions 36 of probes 118 engage contact pads
formed on an upper surface of the personality board. Spring
plungers 210 extend upward from personality board 114 and are
retained within spring housings 212 provided at peripheral portions
of the fixture. Return compression springs 214 are seated atop
spring plungers 210 with opposite ends of the springs engaging top
plate 202 to bias top plate 202 and alignment plate 204 upward.
Upward travel of top plate 202 is limited by engagement of the head
portions of spring plungers 210 with lower necked portions of
spring housings 212.
Guide pins 216 and guide bushings 218 maintain alignment between
the personality board 114, fixture 200 and a printed circuit board
230 of a unit under test (UUT). The guide pins 216 are positioned
at peripheral portions of personality board 114 to engage
corresponding guide bushings extending through top plate 202 and
alignment plate 204 to engage UUT gasket 220. Peripheral portions
of printed circuit board 230 rest on UUT gasket 220 to position the
printed circuit board parallel to and above top plate 202.
A frame member 222 is positioned atop personality board 114 with
fixture 200 and printed circuit board 230 located within the frame
opening. A lower surface of frame member 222 includes a fixture
gasket 224 made of a resilient material. The gasket provides a
compressible air seal between frame member 222 and underlying
personality board 114. An upper surface of frame member 222
includes a flange on which UUT gasket 220 is seated.
The combination of personality board 114, frame member 222, fixture
200 and printed circuit board 230 form a closed chamber. When the
chamber is subjected to atmospheric pressure as shown in FIG. 13
frame member 222, fixture 200 and printed circuit board 230 resting
thereon are biased upward, away from personality board 114 by
return spring 114. In this "free state", component leads 232 and
printed circuit pads 234 located an the lower surface of printed
circuit board 230 are spaced above personality board 114 whereby
the upper contact terminals of twist probes 118 are spaced apart
from printed circuit board 230. Upon application of a vacuum source
to the chamber, printed circuit board 230 is drawn down under
atmospheric pressure into engagement with twist probes 118 as shown
in FIG. 14. Alternate mechanical activation of the fixture is
possible.
FIG. 19 is a view of a coaxial double-headed twist probe according
to another embodiment of the invention. In FIG. 19, coaxial
double-headed twist probe 320 includes a tubular housing 322 with a
bulge forming press ring 328 for retaining the coaxial twist probe
housing in a support member in for example, frame 130 in TAC module
110 of FIGS. 11 and 12. Coaxial double-headed twist probe 320 also
includes crimped portions 329 and 327 which prevent front and rear
shields 370 and 380 from separating from tubular housing 322.
Finally, coaxial double-headed twist probe 320 includes contact
tips 360 and 338 for connection between, for example, test
components and a personality board as illustrated in FIGS. 11 and
12.
FIG. 20 is a partial cross sectional view of a coaxial
double-headed twist probe according to another embodiment of the
invention. In FIG. 20, coaxial double-headed twist probe 320
includes a tubular housing 322 with press ring 328 and open ends
331 and 336. A tubular plunger 332 is slidably positioned within
rear insulator 310, extending outward through aperture 323 and
terminating in contact tip 338. Tubular plunger 332 is coaxial with
housing 322 and rear insulator 310. Opposing rod-like plunger 350
is slidably positioned within front insulator 300, extending out
from housing 322 through aperture 324 and terminating in contact
tip 360.
Front insulator 300 is coaxial with housing 322 and rear insulator
310. In addition, front insulator 300 is slidably positioned within
rear insulator 310. Front and rear insulators 300 and 310 are
partially disposed within open ends 330 and 337 of front and rear
shields 370 and 380, respectively. Front and rear insulators 300
and 310 are biased by movement of the front and rear shields 370
and 380. In addiction, front and rear shields 370 and 380 are
biased against each other via spring 371 disposed within cavity 325
of housing 322. Spring 371 is preferably made of a spring material
such as stainless steel, music wire or beryllium copper. Inward
travel of front and rear shields 370 and 380 is against an outward
bias provided by spring 333. While spring 371 is shown as a
spirally wound structure, other spring mechanisms are also
contemplated which can outwardly bias front and rear shields 370
and 380.
An internal twisted rod portion 354 of plunger 350 is shaped like a
drill bit or slotted helix, extending through a matching aperture
or keyway 344 of plunger 332. Plunger 350 is preferably identical
to plunger 50 illustrated in FIGS. 6 and 7. In addition, plunger
332 is preferably identical to plunger 30' illustrated in FIGS.
15-18. Both plungers 332 and 350 are free to rotate and
longitudinally translate within housing 322 and front and rear
insulators 300 and 310. External portions of plungers 332 and 350
are preferably made of a conductive substance such as heat treated
beryllium copper (BeCu) or hardened steel plated with gold over
nickel. Housing 322 is preferably made of a material such as deep
drawn gold plated brass or nickel silver.
Plunger 332 includes lengthwise contiguous an internal barrel
portion and an external probe portion which axially extends out
through aperture 323 of rear insulator 310 and housing 322. A
shoulder portion 342 of rear insulator 310 limits travel of plunger
332, maintaining the plunger within housing 322 by engaging a
restricted portion of the aperture formed by counter-sinking rear
insulator at shoulder portion 342. The internal barrel portion of
plunger 332 serves as a seat or stop for spring 333 which biases
plunger 332 outward from housing 322 and against plunger 350.
Plunger 350 axially extends through an opposite aperture or cavity
in front insulator 300 and includes an internal twist rod portion
354 within the front insulator and an external probe portion 358
having a terminal contact tip 360. Internal twist rod 354 is
helically formed and includes a twisted bearing surface. Internal
twist rod 354 passes through an aperture forming a keyway 344 in an
internal terminal end of barrel 332. Keyway 344 engages twist rod
354 so that axial travel of the plungers 332 and 350 results in
relative rotation of contact tips 338 and 360.
Although the keyway and matching bearing surface of plungers 330
and 350 are preferably comprised of inward protruding tabs or
"divots" engaging a channel as shown in FIGS. 3-5 and FIGS. 15-18.
However, other geometric shapes can also be used. For example,
keyway 344 may comprise a rectangular aperture to engage a plunger
having a corresponding mating rectangular cross-section. The
tab/channel combination, however, has the advantage of increasing
plunger-to-plunger contact surface area thereby minimizing
electrical resistance through the probe.
Spring 333 is positioned within the cavity of front and rear
insulators 300 and 310, coaxially surrounding the barrel of plunger
332 and twisted rod 354 of plunger 350. Spring 333 is preferably
made of a spring material such as stainless steel, music wire or
beryllium copper. While spring 333 is shown as a spirally wound
structure, other spring mechanisms are also contemplated which can
outwardly bias plungers 332 and 350. Opposite ends of spring 333
are seated on and engage a shoulder portion of plunger 332 and
shoulder and collar portions 363 and 362 of plunger 350,
respectively, thereby biasing plungers 332 and 350 outward from the
housing 322 and from each other. Inward travel of plungers 332 and
350 is against an outward bias provided by spring 333.
Housing 322, prior to assembly of the coaxial double-headed twist
probe, is shown in FIG. 21 of the drawings. The housing has a
substantially tubular body with an aperture 324 formed at one end
while an opposite end 326 remains open For insertion of the
remaining probe components. A bulge in the housing forms press ring
328 for retaining the twist probe housing in a support member.
After plunger 330, spring 333 and plunger 350 are inserted into
housing 322. Next, front and rear insulators 300 and 310 may be
placed in housing 322 around plungers 332 and 350. Front and rear
insulators are held in place via front and rear shields 370 and
380. Front shield 370 may be inserted via aperture 331 of housing
322 which is then crimped at 329 to secure the front insulator and
front shield 300 and 370 structure. Rear shield 380 may be then
inserted via aperture 336 of housing 322 which is then crimped at
327 to secure the rear insulator and rear shield 310 and 380
structure.
FIG. 22 is a sectional view of a rear insulator of the coaxial
double-headed twist probe of FIG. 20. As shown in FIG. 22, rear
insulator 310 includes a first cavity 311 forming opening 335 for
receiving front insulator 300, plungers 332 and 350 with spring 333
biasing plungers 332 and 350. Cavity 311 is counter-sinked at 312
to facilitate compression of spring 333. Rear insulator 310 further
includes a second cavity 313 which is smaller than first cavity 311
for receiving the shoulder portion of plunger 332 and a portion of
spring 333 which abuts the shoulder portion of plunger 332. Cavity
313 is counter-sinked at 314 to form shoulder portion 342 which
limits travel of plunger 332. Shoulder portion 342 maintains the
plunger within housing 322 by engaging a restricted portion of the
aperture formed by counter-sinking rear insulator at 314 forming
shoulder portion 342.
Rear insulator 310 further includes third cavity 315 resulting in
opening 323 for receiving contact tip 338 of plunger 332 and
permitting contact tip 338 external contact. Rear insulator 310
also includes lip 316 which abuts rear shield 380 and which is
influenced by rear shield 380. In particular, rear insulator 310 is
driven inward toward the center of the coaxial double-headed
contact probe 320 by the inward movement of rear shield 380. Rear
insulator 310 further includes shaved tip 317 at opening 335 to
facilitate compression of spring 371 upon the inner movement of
front and rear shields 370 and 380.
FIG. 23 is a sectional view of a front insulator of the coaxial
double-headed twist probe 320 of FIG. 20. As shown in FIG. 23,
front insulator 300 includes a first cavity 302 which is
counter-sinked at 301 forming opening 334 for receiving plungers
332 and 350 with spring 333 biasing plungers 332 and 350. Cavity
302 is counter-sinked at 301 to facilitate compression of spring
333. Front insulator 300 further includes a second cavity 304
forming opening 324. Cavity 304 is smaller than the first cavity
302 for receiving the narrower external probe portion 358 of
plunger 350 which includes contact tip 360. Cavity 304 is
counter-sinked at 303 to facilitate engagement with the shoulder
portion 362 of plunger 350. Cavity 304 and counter-sink 303
maintains the plunger 350 within housing 322 by engaging shoulder
portion 362 with counter-sink 303.
Front insulator 300 also includes lip 307 adjoining section 308
which abuts front shield 370 and which is influenced by front
shield 370. In particular, front insulator 300 is driven inward
toward the center of the coaxial double-headed contact probe 320 by
the inward movement of front shield 370. Front insulator 300
further includes shaved tip 306 at section 305 to facilitate
compression of spring 371 upon the inner movement of front and rear
shields 370 and 380. Section 305 is narrower than section 308 for
insertion in opening 335 of rear insulator 310. Further, section
308 is constructed for insertion in opening 330 of front shield
300.
Front and rear insulators 300 and 310 may be made of any insulating
material which is able to insulate the inner plunger combination of
plungers 332 and 350 from housing 322, front and rear shields 370
and 380 and spring 371. Front and rear insulators 300 and 310 are
preferably made of foamed polyethylene material which provides
these acceptable characteristics while also being easy to work with
and shape described above in connection with FIGS. 22 and 23.
FIGS. 24 and 25 are sectional views of respective front and rear
shields of the coaxial double-headed twist probe 320 of FIG. 20.
FIG. 24 illustrates front shield 370 with opening 330 finely
knurled to form saw teeth 377. Alternatively, instead of saw teeth
377, opening 330 may be in the shape of a flat ring. Front shield
370 also includes section 372 which is insertable in opening 331 of
housing 322. Part of section 372 is external to housing 322 for
contacting an external surface which may or may not be the same
surface which is contacted by contact tip 360. Section 372 adjoins
narrow section 374 which is bordered by angled or slanted surfaces
373 and 375 of front shield 370. Narrow section 374 is constructed
to receive crimped portion 329 of housing 322. Angled surfaces 373
and 375 restrict the movement of front shield 370, i.e., angled
surface 373 prevents front shield 370 from being inserted too far
into housing 322, and angled portion 375 prevents front shield 370
from exiting housing 322. Angled surface 373 and 375 are angled to
facilitate engagement with crimped portions 329 of housing 322
which have a similar angled surfaces.
FIG. 25 is a sectional view of rear shield 380 of the coaxial
double-headed twist probe 320 of FIG. 20. In FIG. 25, rear shield
380 with opening 337 finely knurled to form saw teeth 381.
Alternatively, instead of saw teeth 381, opening 337 may be in the
shape of a flat ring for enhanced connection. Rear shield 380 also
includes section 382 which is insertable in opening 336 of housing
322. Part of section 382 is external to housing 322 for contacting
an external surface which may or may not be the same surface which
is contacted by contact tip 338. Section 382 adjoins narrow section
384 which is bordered by angled or slanted surfaces 383 and 385 of
rear shield 380. Narrow section 384 is constructed to receive
crimped portion 327 of housing 322. Angled surfaces 383 and 385
restrict the movement of rear shield 380, i.e., angled surface 383
prevents rear shield 380 from being inserted too far into housing
322, and angled portion 385 prevents rear shield 380 from exiting
housing 322. Angled surface 383 and 385 are angled to facilitate
engagement with crimped portions 327 of housing 322 which have a
similar angled surfaces.
Front and rear shields 370 and 380 may be any suitable conductive
material, and are preferably made of a material such as gold plated
brass or heat treated gold plated BeCu. Front and rear shields 370
and 380 provide for or conduct additional signals which may enhance
the transmission of the signal through plungers 332 and 350 and
spring 333 by providing ground potential with respect to the
transmitted signal. Alternatively, front and rear shields 370 and
380 may provide a medium for simultaneously transmitting a second
signal with the assistance of spring 371 and housing 322.
Front and rear insulators 300 and 310 are used to isolate or
insulate the signal which is transmitted via plungers 332 and 350
with the assistance of spring 333 for fine or enhanced signal
transmission. Note that for plungers 332 and 350, the signal
transmitted therethrough is not conducted by housing 322 which
significantly isolates the signal from the outside. In addition,
front and rear insulators 300 and 310 are also used to insulate the
signal which is conducted via front and rear shields 370 and 380
with the assistance of spring 371 and housing 322. In this
application, it is presumed that the signal carried therethrough
does not require the isolated conditions of the signal discussed
above which is conducted through plungers 332 and 350 since this
signal is conducted via housing 322 which may be adversely affected
by the area or region which is external to the coaxial
double-headed spring loaded contact probe. When front and rear
shields 370 and 380 are used to conduct a second data signal, the
coaxial double-headed twist probe provides the further advantage of
transmitting two different signals while effectively and
efficiently using the limited space allocated.
FIG. 26 is a side view of a plunger after twisting to form a spiral
channel. In FIG. 26, plunger 350 includes an internal rod portion
forming internal twist rod 354. Plunger 350 is preferably similar
to plunger 50 shown in FIGS. 6 and 7 where plunger 350 is twisted
120 degrees so that a spiral groove is formed resulting in twisted
channel 364b shown in FIG. 26. Channel 364b is configured to engage
keyway 344 of plunger 332 whereby relative axial movement of the
plungers also causes relative rotation of the plungers. Collar
portion 362 of plunger 350 limits axial travel of the probe and
forms a seat for the opposite end of spring 333, biasing plunger
350 outward of housing 322 and against plunger 332. Shoulder
portion 363 abuts collar portion 362 on the inner portion of
plunger 350 and engages an inner surface of spring 333 to maintain
coaxial alignment of the spring within housing 322.
FIG. 27 is a cross-sectional view of exterior portion 358 of
plunger 350 taken along section lines 27--27 of FIG. 26. In FIG.
27, the exterior portion 358 near the contact tip 360
counter-sinked using a standard counter-sink tool to form
counter-sink area 365. The exterior portion 358 is then slotted in
a star shape using a standard V-shape cutting tool to form opening
366. Advantageously, this counter-sinked star-shaped opening
provides the necessary structure to remove dirt or dust from the
contact area of contact tip 360 by drawing the debris into
star-shaped opening 366 or by expelling the debris from the contact
tip.
FIGS. 28-29 are views of a coaxial double-headed twist probe
according to another embodiment of the invention. FIGS. 28-29 are
similar to the coaxial double-headed twist probe illustrated in
FIGS. 19-20, except with respect to including a tapered end shield.
In FIGS. 28-29, both end shields 370, 380 include tapered ends 390.
Tapered ends 390 facilitate electrical contact between the coaxial
double-headed twist probe and an external electrical contact, such
as a coaxial surface contact described in detail below. Note that
while FIGS. 28-29 illustrate a coaxial double-headed twist probe
assembly, a single-headed coaxial probe assembly may also be used
with or without "twist" probes. Similarly, the coaxial
double-headed probe assembly may also be constructed without the
use of twist probes, but rather using probes that are merely
outwardly biased.
FIGS. 30-31 are views of a coaxial surface contact or mate
according co another embodiment of the invention where the inner
plungers or probes are not of the "twist" type described
previously. In FIG. 30, coaxial surface contact 392 includes heat
shrink tubing 394 with an internal band of solder disposed therein
for receiving a coaxial cable via opening 401 and connecting
thereto. Outer shield 396 having inspection hole 402 is connected
to heat shrink tubing 394 via the solder band disposed in heat
shrink tubing 394, as will be discussed in greater detail below. A
second outer shield 414 is connected to the first outer shield 396
via conventional means such as crimping, soldering and the
like.
A second outer shield 414 includes mechanical stop 422 which
prevents the coaxial surface contact from being inserted too far
into, for example, an interchangeable test adapter wiring module
(see, for example, FIGS. 28-29 of U.S. patent application Ser. No.
08/344,575 filed Nov. 18, 1994, the specification of which is
incorporated herein by reference).
Outer shield 414 also includes retaining rings 420 which are used
to prevent coaxial surface contact 392 from being easily dislodged
from, for example, the interchangeable test adapter wiring module,
once coaxial surface contact 392 is inserted therein. Coaxial
surface contact 392 includes opening 403 for mating with or
providing electrical connection with at least one end of the
coaxial spring probe assembly described above.
FIG. 31 is a partial sectional view of the coaxial surface contact.
In FIG. 31, coaxial surface contact 392 includes two separate heat
shrink tubings 394. The outer heat shrink tubing engages with the
outer insulation/shield of the coaxial cable. The inner section of
heat shrink tubing 394 engages the inner conductor of the coaxial
cable. Outer shield 396 includes solder access hole 398 and
inspection hole 402. Solder access hole 398 is used to permit the
outer insulator/shield of the coaxial cable to be fixed to the
outer heat shrink tubing 394 via solder connection 400 when solder
connection 400 is heated. Inspection hole 402 is used to permit the
inner heat shrink tubing 394 to be heated, thereby connecting inner
conductor of the coaxial cable to the inner heat shrink tubing via
solder connection 404.
Coaxial surface contact 392 also includes center conductor 406
terminating at protruding end 408. Center conductor 406 is to be in
electrical connection with the center conductor of the coaxial
cable via solder connection 404 in the inner heat shrink tubing
394. Coaxial surface contact 392 further includes insulator 410
which substantially surrounds center conductor 406. Insulator 410
terminates at outer end 412 which is disposed or configured to be
slightly behind protruding end 408 of conductor 406, as will be
explained in greater detail below. Insulator 410 of coaxial surface
contact 392 is substantially surrounded by a combination of two
outer shields, outer shield 396 and outer shield 414.
Outer shields 396 and 414 are affixed to each other via
conventional means, such as crimping and/or soldering connections,
and the like. The combination of outer shields 396 and 414 provides
electrical connection between the outer shield of the coaxial cable
and the outer shields of the coaxial spring probe assembly
described in more detail below. Insulator 414 is affixed within
coaxial surface contact 392 via the crimping action used to connect
outer shields 396 and 414 together.
Outer shield 414 is shaped at its outer end 418 for receiving or
mating with a conical shaped or tapered surface. Advantageously,
this configuration of outer shield 414 greatly enhances the
electrical contact between outer shield 414 and its mating surface.
Outer shield 414 also includes retaining rings 420 and mechanical
stops 422, as described in detail above.
FIG. 32 is a partial cross-sectional view illustrating the
engagement between a coaxial surface contact and a coaxial probe
that does not require twist plungers according to another
embodiment of the invention. As illustrated in FIG. 32, outer
shield 370 of coaxial spring probe 320' engages outer shield 414 of
coaxial surface contact 392 via mating of conical shaped surfaces
390 and 418.
Conical or angularly shaped surfaces 390 and 418 advantageously
provide a secure connection between coaxial spring probes 320' and
coaxial surface contact 392. Conical shaped surfaces 390 and 418
also prevent transverse movement between coaxial spring probe 320'
and coaxial surface contact 392, thereby providing a more secure
connection therebetween. When coaxial spring probe 320' engages
with coaxial surface contact 392, insulator 300 also engages
insulator 410 as spring probe 358' is depressed when engaged with
center conductor 408.
FIG. 33 is an illustration of the complete engagement between the
coaxial spring probe assembly 320' and coaxial surface contact 392.
As clearly illustrated in FIG. 33, coaxial spring probe assembly
320' is securely connected to coaxial surface contact 392,
particularly with respect to transverse movements.
In summary, the double-headed twist probe and the coaxial
double-headed twist probe according to the invention provides
direct electrical conductivity between circuitry mounted on
parallel substrates, avoiding intermediate connectors and wiring.
By mounting a plurality of double-headed twist probes or a
plurality of coaxial double-headed twist probes in a suitable
supporting member, a double-sided "bed of nails" configuration is
achieved to form a TAC module. The TAC module accommodates
simplified removal and replacement of frequently changed circuit
board mounted components, such as testing equipment personality
boards.
In addition, the coaxial surface contact and the coaxial spring
probe assembly provide a unique structure and process for coaxial
connections. For example, one of the features of the double-headed
coaxial spring probe assembly is that the internal plungers are
outwardly biased against each other. Further, the outer shields of
the double-headed coaxial spring probe assembly are also or
alternatively outwardly biased against each other. The
double-headed coaxial spring probe assembly advantageously
outwardly biases the insulator cores using the outward bias of the
inner plungers.
The insulators in the coaxial spring probe assembly are
advantageously biased inwardly via compression of the outer shields
when the outer shields engage with an external surface. Thus, the
insulators and outer shields remain essentially in the same plane
of contact. Further, both the coaxial spring probe assembly and the
coaxial surface contact include outer shields with tapered ends (or
conical-like shape), thereby providing more secured connection
therebetween, particularly with respect to transverse movement.
Significantly, the coaxial spring probe assembly includes
components that are movably connected to one another, and does not
necessarily require solder-like connection therein. Rather,
internal components of the coaxial spring probe assembly are
movably connected to one another.
While the double-headed coaxial spring probe assembly has been
illustrated, it should also be noted that a single-headed coaxial
assembly is also possible which includes many of the important
aspects of the double-headed coaxial spring probe assembly. In
addition, a coaxial double-headed spring probe assembly can be used
with twist plungers or with plungers that are merely outwardly
biased in any conventional manner.
Although the present invention has been described and illustrated
in detail, it is clearly understood that the same is by way of
illustration and example only and is not to be taken by way of
limitation, the spirit and scope of the present invention being
limited only by the terms of the appended claims.
While there have been described and illustrated several specific
embodiments of the invention, it will be clear that variations in
the details of the embodiments specifically illustrated and
described may be made without departing from the true spirit and
scope of the invention as defined in the appended claims.
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